The engineers know!
When I bought what was left of my CBR600F2 I picked the brains of a buttload of folks on their forum site. A lot of fellas were buying up the later F3 rims to convert up to a 200 series tire. Mine was already set up that way and handled decently. After reading all I could I decided to go back to the thinner F2 rim and the 180 (stock) size rear.
WOW! The bike went from handling decent to being the most flickable thing on the canyon. I can even pass inside my buddy on his Ducati 999 in a tight sweeper. If the scoot came with 240 tire, there's a reason for it. (get power to the ground?) if it came with a 180, there was probably a reason for that too. Besides, nobody is going to be able to tell the difference with the naked eye so if it doesn't improve performance, or look cooler why spend the money?
In vino, veritas!